Surface finish gauges having a small probe tip radius and a high data density are frequently used to measure the surface roughness of manufactured products. Very often, the surface finish of a manufactured product, for example, a crankshaft, is measured on an audit basis—i.e., not every part is measured, but rather, only a statistical sample is checked. Products with unacceptable surface finish characteristics may not be detected if there is only an intermittent manufacturing problem. One example of this is found in the case of crankshaft polishers not functioning correctly. Even if a problem is detected during the statistical sampling of surface finish measurements, it may not be detected in time to keep a component from being assembled in an engine or other large assembly. This can create additional downtime and expense as assemblies must be quarantined, and then ultimately disassembled to have the defective components replaced.
In contrast to surface measurements, some types of measurements in high volume production are taken on every product that is manufactured for in-line monitoring. For example, with some manufactured products, such as a crankshaft, every part may have diameter measurements taken at various locations to ensure compliance with specifications. Such measurements for in-line size evaluation are typically performed using much larger probe tips, and have lower data density, when compared to audit surface roughness gauges. The diameter measurement data is typically analyzed and then discarded once it has been determined that the crankshaft meets the required size specifications. Because this data is available for every part—as opposed to a statistically sampled subset of surface roughness data—it would be desirable to use this data to indicate other product parameters, such as a surface finish characterization—e.g., to determine whether the part surface is properly finished.